Frustration

I am very frustrated for what happened with me today with one of my close friend. She had a small but effective work which she asked me for help, in the process of completing that work i called her just to listen that she is busy & she said that she will call me back, its been 3 days since I've seen a text or call from her.

I never regret myself for helping someone but if they don't even have time to speak for their own work that makes me very frustrated.